Cervical spondylotic myelopathy in elderly people: a high incidence of conduction block at C3-4 or C4-5

Abstract

Objectives-To precisely localise the site of conduction block in elderly patients with cervical spondylotic myelopathy in the presence of multilevel compression shown by MRI. Methods-A total of 44 patients aged 65 and older underwent serial intervertebral recording of spinal somatosensory evoked potentials (SSEPs) from either the intervertebral disc or the ligamentum flavum after epidural stimulation. The site of conduction block identified by abrupt reduction in size of the negative peak was designated as the 0 level with the other levels numbered in order of distance assigning a minus sign caudally. Results-A single site of focal conduction block was disclosed in 42 patients, 23 (55%) at C3-4, 17 (40%) at C4-5, and two (5%) at C5-6. At these levels (0), the amplitude of the negative component was reduced (p<0.0001) to 29% and the area to 22%, with a concomitant increase (p<0.0001) of the initial positive component to 150% in amplitude and 293% in area as compared to the−2 level which was taken as the baseline (100%). Conclusions-A high incidence (95%) of focal conduction block at C3-4 or C4-5 with normal conduction at C5-6 and C6-7 characterises cervical spondylotic myelopathy in elderly people. Incremental SSEP studies documenting the site of conduction block will help exclude clinically silent cord compression, directing the surgical intervention to the appropriate level of concern. (J Neurol Neurosurg Psychiatry 1999;66:456-464)

The effects of surgery on locomotion in elderly patients with cervical spondylotic myelopathy

“…Another assumption is that recovery from long-tract signs such as gait disturbance may be more marked if the decompression area is large and cranial. The intervertebral levels involved, as determined by radiographic and electrophysiological analyses in elderly patients, were previously reported to be C3-C4 or C4-C5 [16][17][18][19][20], and the results of this study concur with this. If this theory is correct, elderly patients may achieve satisfactory recovery because the primary lesion can be located more cranially in these patients than in younger patients.…”

Effects of differences in age and body height on normal values of central motor conduction time determined by F-waves

“…Some elderly subjects are diagnosed with asymptomatic spinal cord compression in radiological findings. 21 Some authors reported that measurement of CMCT was valuable for diagnosis of CCM and CTM. 2,3,22 CCM consists of cervical spondylotic myelopathy (CSM), ossification of the posterior longitudinal ligament (OPLL), and other degenerative disease.…”

Preoperative diagnosis of the responsible level in CCM using CMAPs: comparison with SCEPs

“…17 Elderly patients with cervical spondylotic myelopathy show multiple cord compression on MRI, but SCEPs usually showed a single level of conduction block and 95% of focal conduction block at the C3/4 or C4/5 level. 18 Azuma et al 19 reported that 78% of patients with cervical ossification of the posterior longitudinal ligament were determined by SCEPs to have a single site of conduction abnormalities and in about 70% the level was C3/4 or C4/5; however, they found multiple cord compression. These reports indicate multiple compression of the spinal cord on radiographic findings can include clinically silent compression.…”